An outlet box for providing electrical connection with busbars within an electric power busway system is described within U.S. Pat. No. 4,820,178 entitled "Outlet Box for Electric Busway System". The box is in the form of an electrically-insulating enclosure having a hinged cover which must be opened to access the busbars.
An electric power busway plug for carrying power from the busbars is described in U.S. Pat. No. 4,957,447 entitled "Electric Power Busway Plug Alignment Arrangement". The busway plug connectors are keyed for insuring that the busbars connect with the corresponding phases within a multi-phase electric distribution system.
Other arrangements for electrically isolating the busbars within an electric power busway system are disclosed in U.K. Patent Application GB 2,270,210 entitled "Busway/Tap-off Box Connection with a Safety Shutter System" and U.S. Pat. No. 4,146,285 entitled "Bus Duct System". In both of these references the safety mechanism is manually retracted to expose the busbars to make connection with the bus plug connectors and is later manually returned to the closed condition to electrically isolate the busbars.
One purpose of this invention is to provide a busbars cover that electrically isolates the busbars when the busway plug is absent while automatically exposing the busbars upon insertion of the busway plug.